diff --git a/Source/Doc/Architecture.md b/Source/Doc/Architecture.md
index f786448e..fe8f4284 100644
--- a/Source/Doc/Architecture.md
+++ b/Source/Doc/Architecture.md
@@ -1438,25 +1438,25 @@ result in a note change.
 The following table shows the mapping of the input value in HL
 to the corresponding octave and note.
 
-+-------------------------------------------------------+
-|       |                    OCTAVE                     | 
-|  Note |-----------------------------------------------+
-|       |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
-|-------|-----|-----|-----|-----|-----|-----|-----|-----+
-| Bb/A# | 0   | 48  | 96  | 144 | 192 | 240 | 288 | 336 |
-| B     | 4   | 52  | 100 | 148 | 196 | 244 | 292 | 340 |
-| C     | 8   | 56  | 104 | 152 | 200 | 248 | 296 | 344 |
-| C#/Db | 12  | 60  | 108 | 156 | 204 | 252 | 300 | 348 |
-| D     | 16  | 64  | 112 | 160 | 208 | 256 | 304 | 352 |
-| Eb/D# | 20  | 68  | 116 | 164 | 212 | 260 | 308 | 356 |
-| E     | 24  | 72  | 120 | 168 | 216 | 264 | 312 | 360 |
-| F     | 28  | 76  | 124 | 172 | 220 | 268 | 316 | 364 |
-| F#/Gb | 32  | 80  | 128 | 176 | 224 | 272 | 320 | 368 |
-| G     | 36  | 84  | 132 | 180 | 228 | 276 | 324 | 372 |
-| Ab/G# | 40  | 88  | 136 | 184 | 232 | 280 | 328 | 376 |
-| A     | 44  | 92  | 140 | 188 | 236 | 284 | 332 | 380 |
-
-### Function 0x54 -- Sound Play (SNDPLAY)
++-------+---------------------------------------------------------------+
+|       |                             OCTAVE                            | 
+|  Note +---------------------------------------------------------------+
+|       |    0  |    1  |   2   |   3   |   4   |   5   |   6   |   7   |
+|-------+-------|-------|-------|-------|-------|-------|-------|-------+
+| Bb/A# |   0   |   48  |  96   |  144  |  192  |  240  |  288  |  336  |
+| B     |   4   |   52  |  100  |  148  |  196  |  244  |  292  |  340  |
+| C     |   8   |   56  |  104  |  152  |  200  |  248  |  296  |  344  |
+| C#/Db |   12  |   60  |  108  |  156  |  204  |  252  |  300  |  348  |
+| D     |   16  |   64  |  112  |  160  |  208  |  256  |  304  |  352  |
+| Eb/D# |   20  |   68  |  116  |  164  |  212  |  260  |  308  |  356  |
+| E     |   24  |   72  |  120  |  168  |  216  |  264  |  312  |  360  |
+| F     |   28  |   76  |  124  |  172  |  220  |  268  |  316  |  364  |
+| F#/Gb |   32  |   80  |  128  |  176  |  224  |  272  |  320  |  368  |
+| G     |   36  |   84  |  132  |  180  |  228  |  276  |  324  |  372  |
+| Ab/G# |   40  |   88  |  136  |  184  |  232  |  280  |  328  |  376  |
+| A     |   44  |   92  |  140  |  188  |  236  |  284  |  332  |  380  |
+   
+### Function 0x54 -- Sound Play SNDPLAY)                    
 
 | _Entry Parameters_
 |       B: 0x54
@@ -1551,6 +1551,26 @@ SND_SN76489    | 0x01  | SN76489    | E: Left channel port, L: Right channel por
 SND_AY38910    | 0x02  | AY-3-8910  | D: Address port, E: Data port
 SND_BITMODE    | 0x03  | I/O PORT   | D: Address port, E: Bit mask
 
+### Function 0x56 -- Sound Duration (SNDDUR)
+
+| _Entry Parameters_
+|       B: 0x56
+|       C: Audio Device Unit ID
+|       HL: Duration
+
+|      _Returned Values_
+|           A: Status (0=OK, else error)
+
+This function sets the duration of the note to be played in milliseconds.
+
+If the duration is set to zero, then the play function will operate in a non-blocking
+mode. i.e. a tone will start playing and the play function will return. The tone will
+continue to play until the next tone is played. I/O PORT are not compatible and will
+not play a note if the duration is zero.
+
+For other values, when a tone is played, it will play for the duration defined in HL 
+and then return.
+
 `\clearpage`{=latex}
 
 System (SYS)
diff --git a/Source/HBIOS/ay38910.asm b/Source/HBIOS/ay38910.asm
index debe3e08..6ddf9c1d 100644
--- a/Source/HBIOS/ay38910.asm
+++ b/Source/HBIOS/ay38910.asm
@@ -56,7 +56,8 @@ AY_FNTBL:
 	.DW	AY_NOTE
 	.DW	AY_PLAY
 	.DW	AY_QUERY
-
+	.DW	AY_DURATION
+;
 #IF (($ - AY_FNTBL) != (SND_FNCNT * 2))
 	.ECHO	"*** INVALID SND FUNCTION TABLE ***\n"
 	!!!!!
@@ -432,6 +433,19 @@ AY_QUERY_DEV:
 	XOR	A
 	RET
 ;
+;======================================================================
+;	SOUND DRIVER FUNCTION - DURATION
+;======================================================================
+;
+AY_DURATION:
+	LD	(AY_PENDING_DURATION),HL	; SET TONE DURATION
+	XOR	A
+	RET
+;
+;======================================================================
+;	NON-BLOCKING INTERRUPT CODE
+;======================================================================
+;
 AY_DI:
 	LD	A, (AY_READY)
 	BIT	1, A
@@ -457,7 +471,7 @@ AY_WRTPSG:
 	CALL	AY_DI
 #IFDEF SBCV2004
 	LD	A,8			; SBC-V2-004 CHANGE
-	OUT	(112),A			; TO HALF CLOCK SPEED
+	OUT	(RTCIO),A		; TO HALF CLOCK SPEED
 #ENDIF
 #IF (CPUFAM == CPU_Z180)
 	IN0	A,(Z180_DCNTL)		; GET WAIT STATES
@@ -475,7 +489,7 @@ AY_WRTPSG:
 #ENDIF
 #IFDEF SBCV2004
 	LD	A,0			; SBC-V2-004 CHANGE TO
-	OUT	(112),A			; NORMAL CLOCK SPEED
+	OUT	(RTCIO),A		; NORMAL CLOCK SPEED
 #ENDIF
 	JP	AY_EI
 ;
@@ -487,7 +501,7 @@ AY_RDPSG:
 	CALL	AY_DI
 #IFDEF SBCV2004
 	LD	A,8			; SBC-V2-004 CHANGE
-	OUT	(112),A			; TO HALF CLOCK SPEED
+	OUT	(RTCIO),A		; TO HALF CLOCK SPEED
 #ENDIF
 #IF (CPUFAM == CPU_Z180)
 	IN0	A,(Z180_DCNTL)		; GET WAIT STATES
@@ -505,7 +519,7 @@ AY_RDPSG:
 #ENDIF
 #IFDEF SBCV2004
 	LD	A,0			; SBC-V2-004 CHANGE TO
-	OUT	(112),A			; NORMAL CLOCK SPEED
+	OUT	(RTCIO),A		; NORMAL CLOCK SPEED
 #ENDIF
 	JP	AY_EI
 ;
@@ -513,6 +527,7 @@ AY_RDPSG:
 ;
 AY_PENDING_PERIOD	.DW	0	; PENDING PERIOD (12 BITS)	; ORDER
 AY_PENDING_VOLUME	.DB	0	; PENDING VOL (8 BITS)		; SIGNIFICANT
+AY_PENDING_DURATION	.DW	0	; PENDING DURATION (16 BITS)
 AY_READY		.DB	0	; BIT 0 -> NZ DRIVER IS READY TO RECEIVE PLAY COMMAND
 					; BIT 1 -> NZ EXECUTING WITHIN TIMER HANDLER = DO NOT DIS/ENABLE INT
 ;
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 8b8c116e..61a1683e 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -2296,7 +2296,7 @@ SND_ADDENT:
 ;	WORD	DRIVER FUNCTION TABLE ADDRESS
 ;	WORD	UNIT SPECIFIC DATA (TYPICALLY A DEVICE INSTANCE DATA ADDRESS)
 ;
-SND_FNCNT	.EQU	6		; NUMBER OF SND FUNCS (FOR RANGE CHECK)
+SND_FNCNT	.EQU	7		; NUMBER OF SND FUNCS (FOR RANGE CHECK)
 SND_MAX		.EQU	3		; UP TO 2 UNITS
 SND_SIZ		.EQU	SND_MAX * 4	; EACH ENTRY IS 4 BYTES
 ;
diff --git a/Source/HBIOS/hbios.inc b/Source/HBIOS/hbios.inc
index 6e25d5f4..3a9933ca 100644
--- a/Source/HBIOS/hbios.inc
+++ b/Source/HBIOS/hbios.inc
@@ -62,6 +62,7 @@ BF_SNDPRD	.EQU	BF_SND + 2	; REQUEST SOUND PERIOD - HL CONTAINS DRIVER SPECIFIC V
 BF_SNDNOTE	.EQU	BF_SND + 3	; REQUEST NOTE - L CONTAINS NOTE - EACH VALUE IS QUARTER NOTE
 BF_SNDPLAY	.EQU	BF_SND + 4	; INITIATE THE REQUESTED SOUND COMMAND
 BF_SNDQUERY	.EQU	BF_SND + 5	; E IS SUBFUNCTION
+BF_SNDDURATION	.EQU	BF_SND + 6	; REQUEST DURATION HL MILLISECONDS
 ;
 ; BF_SNDQUERY SUBCOMMANDS
 BF_SNDQ_STATUS		.EQU	0
diff --git a/Source/HBIOS/sn76489.asm b/Source/HBIOS/sn76489.asm
index 220e07e3..0590d256 100644
--- a/Source/HBIOS/sn76489.asm
+++ b/Source/HBIOS/sn76489.asm
@@ -262,7 +262,7 @@ SN7_APPLY_PRD:
 
 	LD	A, L			; GET LOWER 4 BITS FOR COMMAND 1
 	AND	$F
-	OR	B			; A NOW CONATINS FIRST PERIOD COMMAND
+	OR	B			; A NOW CONTAINS FIRST PERIOD COMMAND
 
 	AUDTRACE(SNT_REGWR)
 	AUDTRACE_A
@@ -299,6 +299,10 @@ SN7_APPLY_PRD:
 	POP	DE
 	RET
 
+SN7_DURATION:
+	LD	(SN7_PENDING_DURATION),HL	; SET TONE DURATION
+	XOR	A
+	RET
 
 SN7_FNTBL:
 	.DW	SN7_RESET
@@ -307,7 +311,8 @@ SN7_FNTBL:
 	.DW	SN7_NOTE
 	.DW	SN7_PLAY
 	.DW	SN7_QUERY
-
+	.DW	SN7_DURATION
+;
 #IF (($ - SN7_FNTBL) != (SND_FNCNT * 2))
 	.ECHO	"*** INVALID SND FUNCTION TABLE ***\n"
 	!!!!!
@@ -317,6 +322,8 @@ SN7_PENDING_PERIOD
 	.DW	0		; PENDING PERIOD (10 BITS)
 SN7_PENDING_VOLUME
 	.DB	0		; PENDING VOL (8 BITS -> DOWNCONVERTED TO 4 BITS AND INVERTED)
+SN7_PENDING_DURATION	
+	.DW	0		; PENDING DURATION (16 BITS)
 
 STR_MESSAGELT	.DB	"\r\nSN76489: LEFT IO=0x$"
 STR_MESSAGERT	.DB	", RIGHT IO=0x$"
diff --git a/Source/HBIOS/spk.asm b/Source/HBIOS/spk.asm
index 168693ce..427bcf4c 100644
--- a/Source/HBIOS/spk.asm
+++ b/Source/HBIOS/spk.asm
@@ -4,6 +4,12 @@
 ;
 ;======================================================================
 ;
+;	LIMITATIONS -	CPU FREQUENCY ADJUSTMENT LIMITED TO 1MHZ RESOLUTION
+;			QUARTER TONES NOT SUPPORTED
+;			DURATION FIXED TO 1 SECOND.
+;			NO VOLUME ADJUSTMENT DUE TO HARDWARE LIMITATION
+;======================================================================
+;
 ;	DRIVER FUNCTION TABLE AND INSTANCE DATA
 ;
 SP_FNTBL:
@@ -13,6 +19,7 @@ SP_FNTBL:
 	.DW	SP_NOTE
 	.DW	SP_PLAY
 	.DW	SP_QUERY
+	.DW	SP_DURATION
 ;
 #IF (($ - SP_FNTBL) != (SND_FNCNT * 2))
 	.ECHO	"*** INVALID SND FUNCTION TABLE ***\n"
@@ -31,6 +38,7 @@ SP_RTCIOMSK	.EQU	00000100B
 ;
 SP_PENDING_PERIOD	.DW	SP_NOTE_C8	; PENDING PERIOD (16 BITS)
 SP_PENDING_VOLUME	.DB	$FF		; PENDING VOL (8 BITS)
+SP_PENDING_DURATION	.DW	0		; PENDING DURATION (16 BITS)
 ;
 ;======================================================================
 ;	DRIVER INITIALIZATION
@@ -303,9 +311,22 @@ BE_END:
 	POP	IX
 	RET				; ALWAYS EXITS WITH SUCCESS STATUS (A=0)
 ;
-;	STANDARD ONE SECOND TONE TABLES AT 1MHZ (UNCOMPENSATED).
+;======================================================================
+;	SOUND DRIVER FUNCTION - DURATION
+;======================================================================
+;
+SP_DURATION:
+	LD	(SP_PENDING_DURATION),HL; SET TONE PERIOD TO ZERO
+	XOR	A
+	RET
+;
+;======================================================================
+;
+;	STANDARD ONE SECOND TONE TABLES AT 1MHZ.
 ;	FOR SP_BEEPER ROUTINE, FIRST WORD LOADED INTO DE, SECOND INTO HL
 ;
+;======================================================================
+;
 #DEFINE	SP_TONESET(SP_FREQ) .DW SP_FREQ/100, 12500000/SP_FREQ
 ;
 SP_TUNTBL: